1. Field of the Invention
The present invention relates to an image pickup apparatus and an endoscope that internally hold a movable lens and include a lens frame provided with a magnet on an outer circumferential surface.
2. Description of the Related Art
An image pickup apparatus that internally holds a movable lens, and includes a movable lens frame is well-known. The movable lens frame that is movable forward and backward in an optical axis direction of the movable lens in a holding frame, thereby allowing the image pickup apparatus to switch over a focal point on an object. Note that, for example, the image pickup apparatus is provided in an insertion section of an endoscope.
A configuration of the movable lens frame that is movable in the holding frame with use of a motor or the like is well-known.
Japanese Patent Application Laid-Open Publication No. 57-108806 discloses a configuration of an image pickup apparatus. The image pickup apparatus includes a magnet provided on an outer circumferential surface of a movable lens frame, includes an electromagnetic coil provided at a position, facing the magnet, on an inner circumferential surface of a holding frame, and uses a voice coil motor that moves the movable lens frame in the optical axis direction by Fleming's left-hand rule in response to magnetic field generated between the magnet and the electromagnetic coil that is fed with a current.
Incidentally, to make the movable lens frame movable in the holding frame, a gap is provided between the outer circumferential surface of the movable lens frame and the inner circumferential surface of the holding frame.
In the image pickup apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 57-108806 or in a typical movable configuration of a movable lens frame using a voice coil motor, a magnetic field is applied to the entire outer circumferential surface of the magnet of the movable lens frame from a plurality of directions in a radial direction of the holding frame by the electromagnetic coil.